1. Field of the Invention
This invention relates to the field of viscous material delivery systems, and more particularly to a sealed viscous material delivery and dispensing apparatus which is designed to be filled and emptied repeatedly without intervening cleaning of the apparatus, and which effectively delivers the vast majority of viscous material from the apparatus.
2. Description of the Prior Art
Vast amounts of viscous materials are used in transportation and industry. Thick, lubricating greases are used to lubricate vehicles and machinery, and thick, viscous chemicals are used in industry. In the food processing arts, cheeses, cream, food pastes and the like must be moved from point to point without excessively degrading the food's quality and freshness. In the manufacture of fine chemicals and pharmaceutical products, viscous materials are often used, and maintaining the quality of these viscous materials is of vital importance.
Delivering and dispensing viscous materials has always presented a challenge to manufacturers because these materials tend to stick to their containers and eventually coat the pumping machinery used to deliver the viscous materials. Prior art methods of delivery viscous fluids have concentrated on establishing and maintaining a fluid tight seal between pushing pistons or follower plates, and sidewalls of the containers of viscous materials. The devices of U.S. Pat. No. 5,248,069 to Consaga et al.; U.S. Pat. No. 5,297,702 to Crosby, et al.; and U.S. Pat. No. 5,312,028 to Hume are all directed to establishing a close seal.
These prior art devices, however, are highly susceptible to disruption if the sidewalls of the viscous material container becomes out of round or are dented. Moreover, the systems of Consaga et al. and Hume in particular, require high precision in all its parts, and require relatively bulky and expensive equipment.
There accordingly remains a need for a sealed system that uses relatively low cost components, which is repeatedly refillable without intervening cleaning and/or re-conditioning of the vessel, which is strong and durable, and which delivers a high percentage of the viscous material from the container.